Journal of Geophysical Research: Space Physics最新文献

{"title":"Excitation of Upper-Hybrid and Whistler-Mode Waves by Electron Velocity Ring Distribution","authors":"Sang-Yun Lee,&nbsp;Peter H. Yoon","doi":"10.1029/2024JA033285","DOIUrl":"https://doi.org/10.1029/2024JA033285","url":null,"abstract":"<p>The magnetospheres of the Earth and other magnetized planets are replete with high-frequency fluctuations, which are sometimes accompanied by multiple-harmonic electron cyclotron waves, and lower frequency waves of the whistler-mode type. Such waves are presumed to be excited by energetic electrons trapped in the dipolar magnetic field, the so-called loss-cone electrons, the electron ring distribution being a highly idealized example. The present paper investigates the stability of electron ring distribution with respect to the excitation of quasi-electrostatic upper-hybrid wave instability as well as the quasi-electromagnetic whistler mode instability that operates near electron cyclotron frequency. By employing a two-dimensional particle-in-cell numerical simulation, it is demonstrated that the relatively early dynamics is dominated by the upper-hybrid wave instability, but over a longer time period it is the whistler mode instability that ultimately determines the final relaxed state. The simulation results are interpreted with the quasilinear theoretical framework.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 2","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Observations of Energetic O+ Ions With Strong Velocity Shear in the Low Latitude Boundary Layer During an Intense Storm Main Phase","authors":"Suping Duan,&nbsp;Anxin Zhang,&nbsp;Lei Dai,&nbsp;Yuntian Hou,&nbsp;Zhaohai He,&nbsp;Chi Wang","doi":"10.1029/2024JA033127","DOIUrl":"https://doi.org/10.1029/2024JA033127","url":null,"abstract":"<p>Using particle and electromagnetic field data from Magnetospheric Multiscale Spacecraft (MMS), we investigate energetic O⁺ ion characteristics in the strong velocity shear regions in the dusk-side low-latitude boundary layer (LLBL) during the main phase of an intense storm on 13 October 2016. In the large velocity reversal regions, O⁺ ion number density is very high, N_o+ ∼ 0.3 cm⁻³. The pitch angle distributions of these energetic O⁺ ions vary distinctly across different energy ranges. The pitch angles of the lower energetic (3–10 keV) O⁺ ions are mostly less than 45° and show a quasi-parallel distribution. Conversely, the pitch angles of the higher energetic (20–40 keV) O⁺ ions are dominantly in the range from 45 to 135°, suggesting a quasi-perpendicular distribution. The quasi-parallel distribution of lower energetic O⁺ ions implies that these O⁺ ions are outflow along the magnetic field line from the dayside high-latitude ionosphere. Intense electric fields in the strong shear flow region can accelerate O⁺ ions to higher energy, altering their motion from along the magnetic field to the transverse direction in the dusk-side LLBL. Our studies present evidence for strong shear flow in the dusk-side LLBL driving energetic O⁺ ions to traverse the magnetic field motion. The quasi-perpendicular distribution of higher energetic O⁺ ions, in the inner edge of the dusk-side LLBL, may provide a new source of ring current energetic particles during the main phase of the intense storm.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 2","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Equatorial Ionization Anomaly X-Pattern Occurrences Observed by the GOLD Mission During Its First 5 Years","authors":"R. E. Daniell,&nbsp;R. W. Eastes,&nbsp;C. R. Martinis,&nbsp;D. K. Karan","doi":"10.1029/2024JA033299","DOIUrl":"https://doi.org/10.1029/2024JA033299","url":null,"abstract":"<p>The Global-scale Observations of Limb and Disk (GOLD) mission has provided an unusual array of upper atmosphere observations from a geostationary platform, including the behavior of the low latitude nighttime ionosphere. One of the features observed by GOLD is the formation of an X-pattern in the Equatorial Ionization Anomaly when its crests collapse near the magnetic equator. This paper discusses the X-patterns that were observed during the first 5 years of the GOLD mission (2018–2023). This catalog reveals that X-pattern occurrences are more frequent during low solar activity, and appear to be driven by changes in the normal low latitude zonal winds. In the longitude region observed by GOLD (approximately 75°W–5°E) they occurred exclusively during the September Equinox-December Solstice-March Equinox seasons, and they were more likely to occur near 45°W longitude, near the point where the geomagnetic equator crosses the geographic equator in the western hemisphere.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 2","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033299","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying Meridional Advection in the Auroral E-Region For a Range of Geomagnetic Activity Levels","authors":"Rafael Mesquita,&nbsp;Stephen R. Kaeppler,&nbsp;Roger Varney,&nbsp;Ashton Reimer,&nbsp;Robert F. Pfaff,&nbsp;John Craven,&nbsp;Mark Conde,&nbsp;Irfan Azeem,&nbsp;Patrick Dandenault","doi":"10.1029/2024JA032952","DOIUrl":"https://doi.org/10.1029/2024JA032952","url":null,"abstract":"<p>The high-latitude E-region wind forcing has been studied extensively at large scales, but studies in auroral-oval-width scales are still sparse. In the auroral region, where the magnetospheric forcing is in the scale size of the aurora, winds can be forced to hundreds of meters per second in the auroral acceleration channel. This can result in large advective accelerations, where even a moderate cross-channel neutral wind could move momentum outside the acceleration channel through advection. In this paper, we use sounding rocket data from Alaska to estimate the meridional advective acceleration of horizontal momentum and other forcing terms for different geomagnetic activity levels. We used the Poker Flat Incoherent Scatter Radar measurements of F-region plasma drifts and E-region electron densities to calculate the magnetospheric Lorentz forcing (MLF). We interpret our results in terms of the gradient wind solution presented in recent study by Larsen et al. (2022, https://www.doi.org/10.1029/2021JA029936). We found that the magnitude of the advective acceleration and MLF generally increase with the sampled geomagnetic conditions in the non-storm time Quiet to Active range. We concluded that while a correlation between advection and geomagnetic activity is indicated but not the only factor at work with our results, the meridional advection can disturb the gradient balance and influence the neutral winds in both zonal and meridional directions. We also show that it is crucial to account for the time evolution of forcing of winds in the scale of 100–1,000s of kilometers when examining aurora-related events.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 2","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA032952","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing Scientific Capacity in Africa – A Report on the 2023 International Space Weather Initiative School and the African Geophysical Society Annual Conference","authors":"Chigomezyo M. Ngwira,&nbsp;Endawoke Yizengaw,&nbsp;Nat Gopalswamy,&nbsp;Antti Pulkkinen,&nbsp;Prospery Simpemba","doi":"10.1029/2024JA033447","DOIUrl":"https://doi.org/10.1029/2024JA033447","url":null,"abstract":"<p>Natural hazards, such as weather in space and the terrestrial environment, have the potential to disrupt critical technologies and infrastructures that contribute to national security and economic advancement. Enhancing our understanding of natural hazards is a central part to developing mitigation strategies to avert their impact on technological assets and/or infrastructure. With the support of the broader scientific community, the International Space Weather Initiative (ISWI) and the African Geophysical Society (AGS) successfully organized two international events in September–October 2023, namely, the ISWI space weather school and the AGS Annual Conference. Both events were locally hosted by the Physics Society of Zambia in Lusaka, Zambia. This paper is a summary report of the two events, highlighting efforts focused on advancing scientific research in Africa. The report also outlines some of the major challenges faced and discusses key considerations for organizing future meetings.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 2","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033447","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"VLF Transmitter Signals Observed by the Cluster Spacecraft Over a Wide Range of Latitudes","authors":"F. Němec,&nbsp;O. Santolík,&nbsp;J. M. Albert","doi":"10.1029/2024JA033621","DOIUrl":"https://doi.org/10.1029/2024JA033621","url":null,"abstract":"<p>Very low frequency transmitter signals can penetrate through the ionosphere and propagate in the inner magnetosphere, being observed by spacecraft instruments with sufficient frequency resolution and range. We use 23 years of measurements performed by the Waves of High frequency and Sounder for Probing of Electron density by Relaxation instrument on board the four Cluster spacecraft at frequencies up to 80 kHz to investigate the observed wave intensities. The transmitter signals are about an order of magnitude more intense during the night than during the day, and they are apparently confined within the plasmasphere. The extensive latitudinal coverage of the measurements allows us to investigate frequency cut-offs observed in the transmitter spectra. These are mostly in line with nonducted propagation, but occasional partial ducting seems to be necessary to explain signals spanning otherwise inaccessible regions. Finally, we compare the observed intensity patterns with the calculations of Starks et al. (2020), https://doi.org/10.1029/2019ja027029. Although overall agreement is obtained, the observed wave intensities tend to be a factor of about 2–3 lower than the calculated intensities.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 2","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033621","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143396775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ionospheric Plasma Parameters Measured by SPIDER-2 Sounding Rocket During a Pulsating Aurora Event","authors":"Judit Pérez-Coll Jiménez,&nbsp;Nickolay Ivchenko,&nbsp;Tima Sergienko,&nbsp;Boris Strelnikov,&nbsp;Jonas Hedin,&nbsp;Daniel K. Whiter,&nbsp;Urban Brändström,&nbsp;Gabriel Giono,&nbsp;Christos Tolis,&nbsp;Yoshihiro Yokoyama,&nbsp;Keisuke Hosokawa,&nbsp;Yasunobu Ogawa","doi":"10.1029/2024JA032939","DOIUrl":"https://doi.org/10.1029/2024JA032939","url":null,"abstract":"<p>The Small Payloads for Investigation of Disturbances in Electrojet by Rockets 2 (SPIDER-2) sounding rocket was launched from Esrange, Sweden, on the 19th of February 2020 at 23:14 UT. It traversed a pulsating aurora event, deploying eight free falling units which provided in situ multi-point measurements of the electric field, magnetic field and plasma parameters. In this article, the measured plasma parameters have been analyzed and compared with each other and with optical measurements obtained by ground based instrumentation. Peaks in electron density, thermal ion flux and optical emission have been found in the <i>E</i> region. Electron density profiles have been derived from the data collected by the Langmuir probes in two free falling units, the electron probes in the main rocket and the wave propagation experiment. A generally good agreement has been found among the different measurements in the up-leg of the trajectory, while the effect of the rocket wake was evident in the down-leg. The observed electron density profile has been found to agree with an incoming flux of high energetic electrons with energies around 20 keV. Auroral pulsations with a periodicity of 1–2 s have been recorded by an onboard photometer, a ground-based high speed camera, and the in situ thermal ion flux. The percentages of variation between the ON and OFF phases of the pulsations have been quantified for these quantities. The brightness measured by the photometer varies up to 68%, while the thermal ion flux measurements show only a 2.5% variation.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 2","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA032939","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143380582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Role of Inductive Electric Fields in Shaping the Morphology, Asymmetry, and Energy Content of the Storm-Time Ring Current","authors":"Jianghuai Liu,&nbsp;Raluca Ilie,&nbsp;Michael W. Liemohn,&nbsp;Gábor Tóth","doi":"10.1029/2024JA033577","DOIUrl":"https://doi.org/10.1029/2024JA033577","url":null,"abstract":"<p>The inductive component of the magnetospheric electric field, which is associated with the temporal change of magnetic field, provides an additional means of local plasma energization and transport in addition to the electrostatic counterpart. This study examines the detailed response of the inner magnetosphere to inductive electric fields and the associated electric-driven convection corresponding to different solar wind conditions. A novel modeling capability is employed to self-consistently simulate the electromagnetic and plasma environment of the entire magnetospheric cavity. The explicit separation of the electric field by source (inductive vs. electrostatic) and subsequent implementation of inductive effects in the ring current model allow us to investigate, for the first time, the effect of the inductive electric field on the kinetics and evolution of the ring current system. The simulation results presented in this study demonstrate that the inductive component of the electric field is capable of providing an additional source for long-lasting plasma drifts, which in turn significantly alter the trajectories of both thermal and energetic particles. Such changes in the plasma drift, which arise due to the inductive electric fields, further reshape the storm-time ring current morphology and alter the degree of the ring current asymmetry, as well as the timing and the peak of the ion pressure. The total ion energy is increasing at a faster rate than the supply of energetic ions to the ring current, suggesting that the inductive electric field provides effective and accumulative local energization for the trapped ring current population without confining additional particles.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 2","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033577","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electron Dynamics Within Dispersive Scale Alfvénic Field-Line Resonances Embedded Within Substorm Auroral Beads","authors":"P. A. Damiano,&nbsp;E.-H. Kim,&nbsp;J. R. Johnson,&nbsp;A. J. Hull,&nbsp;S. Wing,&nbsp;C. C. Chaston,&nbsp;P. A. Delamere","doi":"10.1029/2024JA033078","DOIUrl":"https://doi.org/10.1029/2024JA033078","url":null,"abstract":"<p>Recent Cluster satellite observations have illustrated that substorm auroral bead formation and currents are associated with the presence of dispersive scale standing Alfvén waves, which are also known as kinetic scale field line resonances (KFLRs) or kinetic Alfvén eigenmodes. In this work, the properties of these waves are further examined using simulations of a gyrofluid-kinetic electron model in conjunction with the Cluster observations at mid-latitudes and Defense Meteorological Satellite Program satellite observations at high-latitudes. These simulations incorporate, for the first time, the effects of both hot magnetospheric and cold ionospheric electron populations within the multi-period evolution of KFLRs. The simulation results demonstrate consistent characteristics with the observed energized electron distributions both at mid- and high-latitudes. Tracing of the energized particle evolution shows that electrons can effectively interact with the wave all along the field line. Quantified energy conversion rates (as determined from <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>j</mi>\u0000 <mo>‖</mo>\u0000 </msub>\u0000 <msub>\u0000 <mi>E</mi>\u0000 <mo>‖</mo>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${j}_{Vert }{E}_{Vert }$</annotation>\u0000 </semantics></math>) show that significant wave energy dissipation occurs at all latitudes with a maximum occurring in the vicinity of the peak in the profile of the magnetic field to density ratio <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mi>B</mi>\u0000 <mo>/</mo>\u0000 <mi>n</mi>\u0000 </mrow>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation> $(B/n)$</annotation>\u0000 </semantics></math>. Additionally, even though dispersive effects lead to the propagation of wave energy across field lines, the particle energization leads to rapid damping of the resonant system in only a few Alfvén periods.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 2","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Plasma Proton Environment Within Saturn's F-G Ring Gap as Observed by the Cassini Plasma Spectrometer Ion Mass Spectrometer During Saturn Orbit Insertion","authors":"E. C. Sittler Jr.,&nbsp;A. K. Woodson,&nbsp;R. E. Johnson,&nbsp;J. F. Cooper,&nbsp;W.-L. Tseng,&nbsp;S. J. Sturner,&nbsp;D. J. Chornay,&nbsp;H. T. Smith,&nbsp;D. G. Simpson,&nbsp;D. B. Reisenfeld","doi":"10.1029/2023JA031614","DOIUrl":"https://doi.org/10.1029/2023JA031614","url":null,"abstract":"<p>We report on the detection of protons and the potential detection of H₂⁺ between Saturn's F and G rings based on Cassini Plasma Spectrometer (CAPS) Ion Mass Spectrometer (IMS) time-of-flight (TOF) composition measurements acquired during Saturn Orbit Insertion (SOI) outbound pass. The range in dipole L shell is 2.3 &lt; L &lt; 2.8. Initial results based on TOF data were presented in E. C. Sittler et al. (2017). Here we present the latest results of our analysis. During the SOI outbound pass between the F and G rings the CAPS IMS was in a mode of reduced post-acceleration voltage at −6 kV instead of the usual −14.6 kV. This reduced voltage still allows the analysis of protons since 6 keV protons are minimally scattered by the instrument's ultrathin carbon foils when compared to heavier ions O⁺ and O₂⁺. Background noise from penetrating radiation and ghost peaks produced by foil-scattered O⁺ ions within the instrument were considered in our analysis. The analysis allowed an determination of the proton density, temperature and flow velocity, accounting for spacecraft potential by assuming a convected Maxwellian for the proton velocity distribution function. We find average proton density n_P = 3.4 ± 1.2 #/cm³, proton temperature T_P = 1.74 ± 0.12 eV, proton corotation flow speed V_P = 24 ± 1.5 km/s in spacecraft reference frame and spacecraft potential Φ_SC = −0.8 ± 1.5 V. These results are compared with previous theoretical estimates of H⁺ and H₂⁺ ions within Saturn's inner magnetosphere.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 2","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JA031614","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}